A line scanner may contain from several hundred to a few thousand and an area imager several thousand to tens of thousand individual picture elements (pixels.) An infrared (IR) imaging array has been described in detail in (1) U.S. Pat. No. 4,080,532, Hopper, 3/1978; (2) U.S. Pat. No. 4,745,278, Hanson, 5/1988; (3) U.S. Pat. No. 4,792,681, Hanson, 12/1988 and (4) "LOW-COST UNCOOLED FOCAL PLANE ARRAY TECHNOLOGY", by Hanson, Beratan, Owen and Sweetser; presented Aug. 17, 1993 at the IRIS Detector Specialty Review. The solid state system described in these references consists of a hybrid circuit arrangement of an IR sensing array electrically bonded to an associated integrated circuit sensing array. Each pixel in these arrays consists of a capacitor that has a heat (IR intensity) sensitive dielectric such as barium-strontium-titanate (BST). BST is a hard ceramic like material which is difficult to pattern into the small geometries required for this application.
One of the methods used to thermally isolate the small capacitive pixels is ion milling as has been described in the references. Ion milling however is not an electrically or chemically clean process and may leave undesired by-products which cause structural and electrical device problems. The common method of reducing these problems is to alter the ion mill parameters such as etch rate, power, vacuum pressure, chemical atmosphere and so on. Because of the numerous variables involved, this solution has proved to be difficult.